Elemental composition of plants from the serpentine soil of Sugashima Island, Japan

Sugashima Island has the largest community of Buxus microphylla in Japan and a unique flora of several serpentine-associated plants. We determined the concentrations of metals (iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr) and strontium (Sr)) and macro elements (potassium (K), calcium (Ca) and magnesium (Mg)) in 75 plants inhabiting this area and considered the key to their adaptation to the high-metal environment. The soil showed typical serpentine characteristics of high Ni, Cr, Co and low Ca : Mg quotient, and the soil pH(H2O) ranged from 6.2 to 8.6. Buxus microphylla had the highest Ni concentration (400 mg kg–1) among the plants collected, and Viola grypoceras and Swertia japonica accumulated over 100 mg kg–1 Ni. Swertia japonica accumulated the highest concentrations of Fe, Cr and Co, and Dendropanax trifidus accumulated the highest concentrations of Mn and Zn. The concentrations of Ni and Fe in the plants, particularly in some alkalophilic plants that are found in areas with calcareous soil in Japan, were significantly correlated. Our results suggested that active Fe uptake could be one of the key characteristics for plant adaptation to and survival on the serpentine soils of Sugashima Island, although the dominance of B. microphylla may be associated with its strong Ni tolerance without accumulating high concentrations of Fe.